iStock/Thinkstock(WASHINGTON) — President Obama said Monday that President-elect Donald Trump told him personally that he would maintain a strong “commitment” to NATO — after the real estate mogul threatened to abandon the alliance during the campaign.

Obama made the remarks at a press briefing at the White House just before departing on his last trip overseas as president, an opportunity he’ll take to signal “solidarity with our closest allies,” he said.

“In my conversation with the president-elect he expressed a great interest in maintaining our core strategic relationships, and so one of the messages I will be able to deliver is his commitment to NATO and the Transatlantic Alliance,” Obama said.

“I think that’s one of the most important functions I can serve at this stage during this trip is to let them know that there is no weakening of resolve when it comes to America’s commitment to maintaining a strong and robust NATO relationship and a recognition that those alliances aren’t just good for Europe,” the president added. “They are good for the United States and they are vital for the world.”

During his presidential campaign Donald Trump described NATO as “obsolete,” while also suggesting he may not honor the organization’s most sacred covenant of mutual defense (an attack on one is an attack on all) in the face of outside aggression.

“If they fulfill their obligations to us, the answer is yes,” Trump told The New York Times in July when asked if he would defend the Baltic states from an attack by Russia.

Trump has said NATO needs to spend more on its own defense and has complained that not every member is in compliance with their obligation to spend 2 percent of gross domestic product on national defense.

Days after the election, NATO’s Secretary-General, Jens Stoltenberg, penned an op-ed in The Guardian warning that “this is no time to question the value of the partnership between Europe and the United States.”

Stoltenberg also issued a stark reminder, seemingly aimed at Trump, that NATO’s mutual defense clause has been invoked only once: when NATO allies deployed in support of the United States after the terror attacks of September 11, 2001.